I use yahoo hosting.
When I go through my access logs I see that when googlebot tries to crawl my site it gets a 500 error from my host - almost all the time.
There are times when all is well and it gets a 200, but I wasnt able to see the pattern.
I'd like to know if anyone else who use yahoo other than me has seen this problem.
Fastest way to check is to point your browser to your access log and search for " 500 ". Putting the spaces around it helps filter out unwanted stuff.